Public Health England, which tracked the numbers, called it the "most exciting development in the UK HIV epidemic in 20 years," reports the Daily Mail.

In fact, according to PHE's Dr. Valerie Delpech, "It is the first time since the beginning of the HIV epidemic in the 1980s that we have observed a decline in new HIV diagnoses among gay and bisexual men."

Researchers point to pre-exposure prophylaxis — a daily dose of medication that has a success rate of up to 99 percent in preventing HIV — as a likely reason for this plunge.

Truvada, the only drug approved for use as PrEP, can be costly. But NHS England, which oversees the budgeting of the country's Department of Health, began funding the use of Truvada as PrEP last August, after a ruling from England's High Court mandated that it do so.